The use of chemicals in the treatment of human hair to achieve a "permanent wave," or "perm," is well known. These processes typically involve the following steps. First, in the "reduction" process, an acid-based chemical solution is applied to the hair and the hair is subjected to mechanical stress by forcing the hair to assume the desired new shape, e.g., by winding a lock of hair around a roller, whereby the combination of mechanical stress and chemical action breaks or "cleaves" the disulfide bonds which link the protein molecules within the hair and are primarily responsible for giving the hair its natural shape. Next, the hair is rinsed to remove as much of the chemical treatment solution as possible and to neutralize any solution which remains in the hair, thereby slowing and eventually stopping the cleavage of disulfide bonds. Next, the hair is treated with an oxidizing agent, such as hydrogen peroxide, which reconstitutes or reforms the broken disulfide bonds in a manner which causes the hair to naturally assume a new shape determined by the applied mechanical stress, and to maintain that shape after the source of the stress is removed. Finally, the hair is removed from the rollers and is rinsed to remove the oxidizing agent. The chemicals used in the conventional permanent wave treatment of hair are so caustic that if the process is repeated too often over a given time period, e.g., more than twice in a year, permanent damage to the hair will result.
It is also well known that the chemical processes described above can be accelerated by the application of heat to the hair mass during the chemical treatment, such as by placing the subject's head in a drying hood. However, because the heat absorption characteristics of keratinic material are very poor, the process of transferring externally applied heat into the interior of the hair shaft is very inefficient and requires uncomfortably high temperatures for relatively long periods.
To solve the heat transfer problem, it has been suggested, in effect, to heat the hair fibers from the inside out rather than from the outside in by the application of an electromagnetic field to the hair during the chemical treatment. The electromagnetic field causes dielectric losses inside the hair fibers which in turn raises the temperature of the fibers from within. One such approach is described in U.S. Pat. No. 3,863,653 issued to Boudouris et al. This technique, however, merely accelerates the chemical reactions, thereby reducing the time that the hair must be exposed to the potentially damaging chemicals, but does not avoid the cumulative adverse effects on the hair, and the environment, caused by these highly caustic agents.